Engine Controls - Basic Testing Mazda 323 BG

INTRODUCTION

The following diagnostic steps will help prevent overlooking a simple problem. This is also where to begin diagnosis for a no-start condition.

The first step in diagnosing any driveability problem is verifying the customer's complaint with a test drive under the conditions the problem reportedly occurred.

Before entering self-diagnostics, perform a careful and complete visual inspection. Most engine control problems result from mechanical breakdowns, poor electrical connections or damaged/misrouted vacuum hoses. Before condemning the computerized system, perform each test listed.

Note. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.

VISUAL INSPECTION

Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and are not pinched or cut. See VACUUM DIAGRAMS article to verify routing and connections (if necessary). Inspect air induction system for possible vacuum leaks.

Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions.

COMPRESSION SPECIFICATIONS

Exhaust System Backpressure

The exhaust system can be checked with a vacuum or pressure gauge. Remove O2 sensor or air injection check valve (if equipped). Connect a 0-5 psi pressure gauge and run engine at 2500 RPM. If exhaust system backpressure is greater than 1 3/4 - 2 psi (.12-/.14 kg/cm 2 ), exhaust system or catalytic converter is plugged.

If a vacuum gauge is used, connect vacuum gauge hose to intake manifold vacuum port and start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge reading slowly drops after stabilizing, exhaust system should be checked for a restriction.

FUEL PRESSURE (CARBURETED)

Basic diagnosis of fuel system should begin with determining fuel system pressure.

Fuel Pump (Electrical)

1. Turn ignition on. Locate fuel control unit under left side of dash. Using a jumper wire, connect terminals "B" to "D". Fuel pump (located in tank) should operate. If pump does not operate, check and replace fuel pump (if necessary). Check fuel pump pressure. See the «FUEL PUMP PERFORMANCE (CARBURETED)»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table. NOTE: Fuel pump control unit terminal identification is not available. FUEL PUMP PERFORMANCE (CARBURETED) Application Pressure: psi (kg/cm 2 ) Min. Vol. In 30 Sec. Pts. (L) B2200 Electrical Pump 2.8-3.6 (.20-.25) 1.1 (.53) Mechanical Pump 3.7-4.7 (.26-.33) .9 (.43)
2. If fuel pump operates, remove jumper wire. With ignition on, backprobe rear of fuel pump control unit. There should be 12 volts on terminals "A" and "D" only. If not, check ignition and power feed.
3. Allow engine to idle. There should be 12 volts on terminals "A", "B", "D" and "F" only. If voltage is missing on terminal "B" only, replace fuel pump control unit. If any other terminal is not as described, check ignition coil (tachometer signal) and power feed.

Fuel Pump (Mechanical)

Test pump for pressure and volume. Replace as necessary. See the FUEL PUMP PERFORMANCE (CARBURETED) table.

FUEL PRESSURE (FUEL INJECTION)

Fuel Pressure

1. Disconnect circuit opening relay. See «CIRCUIT OPENING RELAY LOCATIONS»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table.
2. To bleed down fuel in system, start engine (if possible) and allow to die. Connect pressure gauge to fuel line at fuel filter. Reconnect circuit opening relay.
3. On Navajo, install EFI Pressure Gauge (T80L-9974-B) to relief valve. Relief valve is located on fuel supply manifold.
4. Turn ignition on. Using a jumper wire, connect terminals of Yellow fuel pump check connector together. See «FUEL PUMP CHECK CONNECTOR (YELLOW) LOCATIONS»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table. On Miata, MX-3, Protege, 323 and 929, jump test connector terminals Fp and ground. If pump runs, check fuel pump circuit and circuit opening relay. FUEL PUMP CHECK CONNECTOR (YELLOW) LOCATIONS Application Location B2600i, Miata, MX-6, 323 & 626 On Firewall, Near Windshield Wiper Motor MPV Near Airflow Sensor Navajo At Right Inner Fender Panel
5. If possible, start engine. Check fuel pressure with vacuum connected to and disconnected from pressure regulator. See «REGULATED FUEL PRESSURE (FUEL INJECTION)»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table. Turn engine off and disconnect jumper wire at fuel pump check connector. Wait 10 minutes and ensure residual pressure is at least 21 psi (1.5 kg/cm 2 ).
6. Operate fuel pump by jumpering fuel pump test connector. Check fuel pump performance. Pinch hose between pressure gauge and fuel filter. DO NOT hold longer than necessary to check pressure. See the FUEL PUMP PERFORMANCE table below. If pump does not meet specifications, check fuel pump circuits, fuel pump, fuel tank, fuel filter or replace fuel pump.

FUEL PUMP PERFORMANCE

REGULATED FUEL PRESSURE (FUEL INJECTION)

Fuel Pump Circuit (Except Navajo)

1. Turn ignition on. On B2200 (PFI), B2600i, MPV, MX-6 and 626, connect terminals of Yellow fuel pump check connector with a jumper wire. See «FUEL PUMP CHECK CONNECTOR (YELLOW) LOCATIONS»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table. On Miata, MX-3, Protege, 323 and 929, attach jumper wire to test connector terminal Fp and to ground in the diagnostic connector, next to battery.
2. Listen for fuel pump operating sound. If there is no sound, check main fuse, circuit operating relay, fuel pump and all electrical connections. On MX-3 and 929, ECU grounds circuit opening relay and operates fuel pump whenever distributor signals are present. On other models, airflow meter grounds circuit opening relay and operates fuel pump whenever airflow is present.
3. If circuit opening relay does not work, see SYSTEM/COMPONENT TESTS or appropriate TESTS W/CODES article.

Fuel Pump Circuit (Navajo)

1. If fuel pressure is zero or low, with ignition off, ensure inertia switch is set. Ensure battery is fully charged. Using a jumper lead, ground FP lead terminal of self-test connector. (Scheme 1) Inertia switch is located under dash to the right of transmission tunnel. With ignition on, engine off and inertia switch electrical connector connected, check voltage at fuel pump inertia switch. If voltage is 10.5 volts or more at both inertia switch terminals, go to step 3).
2. If voltage is 10.5 volts or more at only one inertia switch terminal, replace inertia switch. If voltage is less than 10.5 volts at both inertia switch terminals, check and repair wiring circuit.
3. With ignition off, ensure connection is okay at pump/sender unit. Turn ignition on, with engine off. Listen for sound of fuel pump operation. If pump is not running, go to next step. If pump is running, check condition of fuel filter. If filter is okay, replace fuel pump. If filter is dirty, replace filter and recheck system.
4. Turn ignition off and disconnect fuel pump/sender connector. (Scheme 1) Turn ignition on, with engine off. Measure voltage at pump power terminal (Pink/Black wire) of pump/sender connector. If voltage is 10.5 volts or more, go to next step. If voltage is not 10.5 volts or more, repair open in Pink/Black wire between fuel pump and inertia switch.
5. With fuel pump/sender connector still disconnected, measure resistance of pump ground wire (Black wire) to chassis ground. (Scheme 1) If resistance is less than one ohm, go to next step. If resistance is not less than one ohm, repair open in Black wire between fuel pump and ground.
6. Turn ignition off. Measure resistance between inertia switch and ground. If resistance is less than 5 ohms, replace fuel pump. For additional circuit testing information see CIRCUIT TEST J in TESTS W/CODES - NAVAJO article.

Scheme 1

Fuel Pump Relay (Navajo)

1. Remove fuel pump relay (located under power distribution box on right inner fender). Connect 12 volts to terminal "C" and ground terminal "D". Check for continuity between terminals "A" and "B". If continuity is present, relay is okay. If continuity is not present, replace relay.
2. Turn ignition on. Ensure 12 volts is present on Red and Black/Yellow or Yellow wires. If 12 volts is not present, repair circuits from Electronic Engine Control (EEC) power relay, battery or power distribution box.
3. Connect 12 volts to terminal "A". Fuel pump should operate. If pump does not operate, repair wiring to inertia switch, fuel pump, fuel pump ground, or replace fuel pump.

Inertia Switch (Navajo)

Inertia switch is located under dash to the right of transmission tunnel. To reset switch, make sure no fuel leaks are present. Push reset button.

Circuit Opening Relay (Except MX-3 1.8L, Navajo & 929)

1. With relay connected, ensure specified voltage is present at relay terminals. See «CIRCUIT OPENING RELAY CIRCUIT VOLTAGES»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table. For location of circuit opening relays, see «CIRCUIT OPENING RELAY LOCATIONS»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table.
2. If voltages are okay, remove relay from vehicle. Check relay operation using a 12-volt battery source and perform resistance tests. (Scheme 2)

Circuit Opening Relay (MX-3 1.8L & 929)

1. With relay connected, ensure battery voltage is present at relay terminal White/Red wire terminal on MX-3 or Black/White wire terminal on 929. For locations of circuit opening relay, see «CIRCUIT OPENING RELAY LOCATIONS»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table.
2. If voltages are okay, remove relay from vehicle. Using a 12-volt battery source, connect 12 volts to relay terminals "A" and "B". Ensure continuity is present across terminals "C" and "D". If not, replace circuit opening relay.

CIRCUIT OPENING RELAY LOCATIONS

CIRCUIT OPENING RELAY CIRCUIT VOLTAGES

Scheme 2

Spark

Check for spark at coil wire and at each spark plug wire using a high output spark tester. Check spark plug wire resistance on suspect wires. Resistance should be no less than 4878 ohms per foot.

Ignition Coil Power Source

Turn ignition on. Using voltmeter, check for 12 volts between positive (+) terminal and ground. If no voltage is present, check battery feed, main fuse, main relay No. 1 (MX-6 and 626 models), ignition switch and fusible links.

Ignition Coil Resistance (Except MX-3 1.8L)

1. Remove primary and secondary leads from ignition coil. Using ohmmeter, check primary resistance between positive and negative terminals of coil. (Scheme 3) Resistance should be as specified in «IGNITION COIL RESISTANCE»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table. If resistance is not as specified, replace ignition coil.
2. Check secondary resistance between (positive) terminal and coil tower. (Scheme 3) See «IGNITION COIL RESISTANCE»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table. If resistance is not within specifications, replace coil.

Ignition Coil Resistance (MX-3 1.8L)

1. Remove primary and secondary leads from ignition coil. Using ohmmeter, check primary resistance between terminals "A" and "C" of coil. (Scheme 4) Resistance should be as specified in «IGNITION COIL RESISTANCE»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table. If resistance is not as specified, replace ignition coil.
2. Check secondary resistance between terminal "C" and coil tower. (Scheme 4) See «IGNITION COIL RESISTANCE»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table. If resistance is not within specifications, replace coil.

Note. (Scheme 3) is Courtesy of Mazda Motors Corp.

Checking Coil (B2200, B2600i, MPV & 929; Others Except MX-3 1.8L Are Similar). Scheme 3

Scheme 4

IGNITION COIL RESISTANCE

Optical Distributor Voltage (Miata, Protege & 323)

1. Turn ignition on. Check optical distributor ignition source by backprobing distributor terminal for correct voltage. See «OPTICAL DISTRIBUTOR VOLTAGE SPECIFICATIONS»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table.
2. Ensure ignition coil has battery voltage. If ignition coil resistance and pick-up coil test okay, check for spark. If spark is still not present, go to appropriate IGNITOR test procedure. If spark is still not present, see appropriate TESTS W/CODES article.

OPTICAL DISTRIBUTOR VOLTAGE SPECIFICATIONS

Distributor Pick-Up Coil Resistance (B2200, B2600i, MPV, MX-6 Non-Turbo & 626 Non-Turbo

1. Disconnect pick-up coil from distributor. Using an ohmmeter, measure resistance between 2 inner terminals on pick-up coil. Replace pick-up coil if resistance is not as specified in «DISTRIBUTOR PICK-UP COIL RESISTANCE»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table.
2. Ensure ignition coil has battery voltage. If ignition coil resistance and pick-up coil test okay, check for spark. If spark is still not present, go to appropriate IGNITOR test procedure. If spark is still not present, see appropriate TESTS W/CODES article.

DISTRIBUTOR PICK-UP COIL RESISTANCE

Crank Angle Sensor Resistance (MX-3 1.8L, MX-6 Turbo, 626 Turbo & 929)

1. Disconnect crank angle sensor connector from distributor. On MX-3 and 929, crank angle sensor is a separate unit located at front of crankshaft. Measure resistance between terminals indicated in «CRANK ANGLE SENSOR RESISTANCE»(/mazda/323/bg-1989-1995/remont/testing-diagnostics/#engine-controls-basic-testing) table. (Scheme 5) If resistance is not as indicated, replace distributor assembly.
2. If ignition coil resistance and crank angle sensor test okay, check for spark. If spark is still not present, go to appropriate IGNITOR test procedure. If ignitor is okay and spark is still not present, see appropriate TESTS W/CODES article.

CRANK ANGLE SENSOR RESISTANCE

Scheme 5

Hall-Effect Sensors (MX-3 & 929)

1. Remove distributor. Remove circuit opening relay and disconnect 3-pin connector from distributor. This will prevent coil sparking. Turn ignition on.
2. Using a voltmeter, backprobe White wire (MX-3 1.6L), Violet/Green wire (MX-3 1.8L) or Green/White wire (929) at distributor. Slowly rotate distributor shaft one turn. Voltmeter should pulse 0-5 volts 4 times (4-cylinder) or 6 times (V6).
3. Backprobe Yellow/Blue (MX-3 1.6L), Violet/White wire (MX-3 1.8L) or Blue wire (929) at distributor. Slowly rotate distributor shaft one turn. Voltmeter should pulse 0-5 volts one time. If either sensor does not work as described, turn ignition off. Disconnect 4-pin or 6-pin connector at distributor.
4. Turn ignition on. Ensure 5 volts is present at same wires which were checked in steps 2) and 3). If 5 volts not present, check wiring and ECU. If 5 volts present, replace distributor assembly.

Ignitor (B2200 w/Carburetor, MX-3 1.8L, MX-6 Non-Turbo & 626 Non-Turbo)

Testing information is not available. If coil, ECU, sensor and wiring are okay, replace ignitor.

Ignitor (B2200 w/PFI, B2600i, Miata, MPV 2.6L, MX-3 1.6L, Protege & 323)

1. Ensure coil and power source are okay before checking ignitor. Disconnect coil ignitor connector. Install Ignitor Checker (49 F018 002) and Adapter Harness (49 N018 011 on MX-3 1.6L, Protege and 323; 49 N018 001 on all others). Connect the ignitor checker and adapter between the ignitor and wiring harness, connect the power leads to the battery.
2. Turn ignition on. Disconnect the high-tension coil lead from the distributor and hold it about 1/4" from ground. Flip the SW2 on and off, and verify a strong Blue spark is discharged from lead. If spark is weak in color, replace the coil. If no spark is present, check battery feed, main fuse, ignition switch and fusible links. Repair or replace as necessary. CAUTION: DO NOT hold the SW2 switch on longer than one second.
3. Turn ignition on. Using voltmeter, check voltage on Black wire of adapter harness. Flip SW2 switch on and off. Verify voltmeter fluctuates. If voltmeter does not fluctuate, replace ignitor and retest.

Ignitor (MPV 3.0L, MX-6 Turbo, 626 Turbo & 929)

1. Turn ignition off. Disconnect ignitor connector and install Test Harness (49 N018 001 on MPV 3.0L and 929 or 49 F018 002 on all others). Using a needle-type ohmmeter, connect (+) lead to ground and (-) lead to single-pin test wire of test harness. CAUTION: Ensure ohmmeter is installed with (+) lead to ground and (-) lead to single-pin wire of test harness. DO NOT reverse leads or damage may result.
2. Connect Ignitor Checker (49 F018 002 on MPV 3.0L and 929 or 49 H018 910 on all others) to other lead of test harness and to battery. (Scheme 6) Set ohmmeter to X1 scale.
3. Turn ignition on. DO NOT touch ignitor checker SW1 switch. Push up ignitor checker SW2 switch and note ohmmeter reading. Ohmmeter needle should jump to 1/2 of the scale and then return. If ohmmeter does not operate as specified, replace ignitor.

Scheme 6

NAVAJO

Note. While performing EDIS diagnostics, DO NOT connect Electronic Control Assembly (ECA) to breakout box unless directed to do so.

Note. Perform following tests in sequence shown, unless test procedures indicate otherwise.

Initial Test

Check for any stored trouble codes and repair as necessary. See appropriate TESTS W/CODES article. Using a high-output spark plug tester, check for spark at all spark plugs. If spark is present at ALL spark plugs, go to CHECK PROFILE IGNITION PICKUP (PIP) AT EDIS MODULE. If no spark is indicated or spark only occurs at some spark plugs, go to CHECKING PLUGS & WIRES.

Scheme 7

1. Turn key off. Connect EDIS Diagnostic Cable (007-00059) to Breakout Box (T83L-50-EEC-IV), EDIS module and coil pack. DO NOT connect Crankshaft (VRS) sensor tee. (Scheme 7) Use EDIS No. 6 overlay.
2. Connect EDIS diagnostic cable negative lead to battery, leaving positive lead disconnected. Set EDIS diagnostic cable box to 4/6 CYLINDER position. Connect LED test light leads between breakout box pins No. J43 (PIP E) and J7 (ground). Crank engine. If LED test light blinks, go to step 3). If test light does not blink, go to ISOLATE EDIS MODULE/PIP FAULT.
3. Turn key off. Disconnect ECA. Check continuity of PIP and Ignition Ground (IGND) wires between EDIS and ECA. (Scheme 8) If any problems are found, repair circuits and components. Clear Continuous Memory, and run QUICK TEST in appropriate TESTS W/CODES article. If continuity is present and wires are not shorted or open, replace EDIS module.

Isolate EDIS Module/PIP Fault

With key off, disconnect ECA. Connect LED test light leads between breakout box pins No. J43 (PIP E) and J7 (ground). Crank engine. If LED test light blinks, replace ECA. If test light does not blink, check PIP for short to ground or power. Repair any problems found. If no problems are found, replace EDIS module.

Checking Plugs & Wires

Crank engine. Using a high-output spark tester, check for spark at both spark plug wires of each coil. If no spark at all coils, go to CHECK FOR VBAT TO EDIS MODULE. If spark is missing from both spark plug wires of one or 2 coils, go to CHECK VBAT OPEN TO COIL. If spark is missing from one wire, replace spark plug wire and spark plug. Recheck ignition system.

Check For VBAT To EDIS Module

Turn key off and disconnect ECA, set DVOM to 20-volt scale. Turn key on. Measure voltage between breakout box pins No. (+) J51 (VBAT E) and (-) J7 (BAT negative). (Scheme 8) If voltage is greater than 10.5 volts, go to CHECK FOR GROUND OPEN TO EDIS MODULE. If voltage is 10.5 volts or less, repair open or short in circuit from ignition switch.

Check For Ground Open To EDIS Module

Turn key off and disconnect ECA. Measure resistance between breakout box pins J27 (PWR GND E) and chassis ground. If resistance is less than 5 ohms, go to CHECK VRS RESISTANCE. If resistance is 5 ohms or more, repair open in ground circuit.

Check VRS Resistance

Turn key off and disconnect ECA. Connect EDIS diagnostic cable negative lead to negative battery terminal. Set DVOM to 20-k/ohm scale. Measure resistance between breakout box pins No. J48 (VRS - E) and J35 (VRS + E). (Scheme 8) If resistance is 2580-2700 ohms, go to VRS SENSOR. If resistance is not 2580-2700 ohms, repair wires between VRS and EDIS or replace VRS.

Scheme 8

VRS Sensor

Ensure trigger wheel on crank pulley and VRS are not damaged. Ensure VRS is not touching trigger wheel. If no problems are found, disconnect EDIS connector. Crank engine and check for A/C voltage at EDIS harness terminals No. 5 and 6. (Scheme 8) If A/C voltage is not pulsing greater than 1 volt, check VRS circuits for opens or shorts. If no problems are found, replace VRS sensor. If A/C voltage pulses greater than 1 volt, go to CHECK VBAT OPEN TO COIL.

Check VBAT Open To Coil

Turn key off, and disconnect harness at coil pack. Turn key on. Measure voltage between coil pack harness terminal No. 4 and ground. If more than 10.5 volts is present, go to next step. If there is less than 10.5 volts, repair open circuit. Remove all test equipment, and reconnect all components. Clear Continuous Memory and check for fault codes.

Verify Coil Operation

Crank engine. If there is no spark, go to CHECK C1, C2 & C3 AT COIL PACK (CRANKING). If spark is present at any coil, go to CHECK C1, C2 & C3 AT COIL PACK (RUNNING).

Check C1, C2 & C3 At Coil Pack (Cranking)

Turn key off. Reconnect harness at coil pack. Set DVOM on 20-volt AC scale. While cranking engine, backprobe between coil terminals No. 1, 2 and 3, and chassis ground. (Scheme 8) If any voltage reading while cranking is NOT 0.2-1.0 volt, go to CHECKING EDIS CONTROL. If all voltage readings while cranking are 0.2-1.0 volt, go to CHECKING COIL PACK.

Check C1, C2 & C3 At Coil Pack (Running)

Turn key off. Reconnect harness at coil pack. Set DVOM on 20-volt AC scale. Start engine, backprobe between coil terminals No. 1, 2 and 3, and chassis ground. (Scheme 8) If any voltage reading while running is NOT 1.0-2.0 volts, go to CHECKING EDIS CONTROL. If voltage reading of each coil (while running) is 1.0-2.0 volts, go to CHECKING COIL PACK.

Checking Coil Pack

Turn key off, and disconnect coil pack. Measure resistance between coil pack terminal No. 4 and all other terminals. (Scheme 8) If each resistance is greater than 0.8 ohm, replace coil pack. If any resistance is less than 0.5 ohm, replace coil pack and EDIS module. Remove all test equipment, and reconnect all components. Clear Continuous Memory and check for fault codes.

Checking EDIS Control

If voltage was less than described in CHECK C1, C2 & C3 AT COIL PACK (RUNNING) or CHECK C1, C2 & C3 AT COIL PACK (CRANKING), replace coil pack. If voltage was greater than described, check circuits between coil pack and EDIS module for opens or shorts. If circuits okay, replace EDIS module. Remove all test equipment, and reconnect all components. Clear Continuous Memory, and check for fault codes.

IDLE SPEED & IGNITION TIMING

Ensure idle speed and base ignition timing are set to specification. If necessary, see ADJUSTMENTS article.

IGNITION TIMING SPECIFICATIONS

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to appropriate TESTS W/CODES article. If no hard codes are found in self-diagnostics, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

See also:
• FUEL PUMP PERFORMANCE (CARBURETED)